1. Field of the Invention
The present invention relates to a pinion stopper for a starter. More particularly, the present invention pertains to a pinion stopper for use in an overhang type starter in which a pinion is disposed forward of a bearing.
2. Description of the Prior Art
FIG. 1 is a sectional view of a conventional pinion stopper used in a front nose type starter. In this figure, reference numeral 1 denotes an armature of a DC motor, and 2 an armature rotary shaft. An epicyclic reduction gear 3 is provided at the forward end of the armature rotary shaft 2. A yoke 4 has permanent magnets 5 producing magnetic fields which are rigidly secured to its inner peripheral surface. Reference numeral 6 denotes an output rotary shaft to which rotational force is transmitted from the epicyclic reduction gear 3. A helical spline 7 is formed on the outer periphery of the output rotary shaft 6, and an overrunning clutch 8 is axially slidably fitted on the output rotary shaft 6 through the helical spline 7. A pinion 9 is connected to the overrunning clutch 8 in one unit, so that the pinion 9 is movable back and forth in the axial direction of the output rotary shaft 8. The numeral 10 denotes a stopper means which is provided on the output rotary shaft 6 to limit the axial movement of the pinion 9. The stopper means 10 comprises a ring 11a fitted in a recess formed in the output rotary shaft 6 and a stopper member 11b which is engaged with the ring 11a. The numeral 12 denotes a sleeve bearing which is provided at the forward end portion of a front bracket 13 to support the forward end portion of the output rotary shaft 6. The numeral 14 denotes a lever formed of a resin material. The lever 14 is pivotally mounted with one end thereof connected to a plunger (not shown) of an electromagnetic solenoid 15 and the other end thereof connected to the rear end of the overrunning clutch 8.
FIG. 2 shows an overhang type starter wherein the pinion is disposed forward of a bearing which is fitted to the front bracket. In this figure, the lower-half of a pinion driving shaft 16 shows the shaft 16 moved forward to mesh with a ring gear 30. The pinion driving shaft 20 which has a gear 20 generated in its distal end portion is supported by a bearing 18 fitted to a front bracket 17. A stopper means 24 is provided forward of the distal end of the pinion driving shaft 16 to limit the axial movement of the shaft 16. The stopper means 24 comprises a ring 26 fitted in a recess 25 formed in the distal end portion of the output shaft 6 and a stopper member 27 which is loosely fitted on the ring 26.
In the above-described starters, when a starting switch is turned on, the electromagnetic switch 15 is actuated. As a result, the DC motor is energized and the armature 1 generates rotational force. At the same time, the plunger of the electromagnetic solenoid 15 is drawn, and the lever 14 is thereby pivoted, thus causing the overrunning clutch 8 and the pinion 9 or 20 to move forward. At this time, the forward end of the pinion 9 or 20 abuts against the stopper means 10 or 27 and the extremity of its axial travel is thus defined. In this position, the pinion 9 or 20 meshes with the ring gear 30 of the engine to start it.
The above-described conventional pinion stoppers of the front nose type and overhang type starters suffer, however, from the following problems.
In either the front nose or overhang type starter, if the diameter of a flywheel of the engine which is located at the rear (as viewed from the starter) of the ring gear 30 is larger than the diameter of the ring gear 30, the output shaft 6 which projects forward from the distal end of the pinion 20, or the front bracket 13 which is located forward of the pinion 9, may interfere with the above-described flywheel. In such a case, it is impossible to select a desired flywheel configuration. Further, in the prior arts, the output shaft 6 with which is slidably engaged the pinion 9 or the pinion driving shaft 16 is partially exposed and there is therefore a fear of the pinion 9 or the pinion driving shaft 16 failing to slide smoothly because of corrosion of the exposed portion or adhesion of dust to it. In one type of conventional starter, the above-described stopper means is provided on that portion of the output rotary shaft 6 where the overrunning clutch 8 is slidably fitted. This prior art has, however, the problems that assembly is troublesome and the structure is complicated.